Effects of long-term exercise training on cardiac autonomic nervous activities and baroreflex sensitivity |
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Authors: | Linda?Massako?Ueno Email author" target="_blank">Toshio?MoritaniEmail author |
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Institution: | (1) Laboratory of Applied Physiology, Graduate School of Human and Environmental Studies, Kyoto University, Sakyo-ku, 606–8501, Kyoto, Japan, |
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Abstract: | Reductions in tonic vagal controls of the heart and depressed baroreflex sensitivity (BRS) have been associated with a postural
fall in blood pressure (BP) and the incidence of cardiac events among older people. We examined the hypothesis that BP regulation
during orthostatic challenge as well as heart rate variability (HRV) at rest can be better maintained in long-term exercise-trained,
healthy, older men (aged 60–70 years). Subjects were classified into two groups; long-term exercise-trained (LTET, n=14) and sedentary (SED, n=10) according to their history of physical activity. Prior to the dynamic BRS assessment, supine resting autonomic cardiac
modulation was assessed by means of time domain HRV standard deviation of ECG R–R interval (RRISD) and the coefficient of
variation (CV)]. The BRS was assessed during 60° head-up tilting by simultaneously measuring beat-by-beat systolic blood pressure
(SBP) and ECG R–R interval changes. The BRS gain was determined by the regression slope coefficient based on the extent of
the SBP fall and the corresponding ECG R–R shortening during the orthostatic challenge. The results indicated that the LTET
group manifested greater ECG R–R interval fluctuations with significantly higher resting RRISD and CV, compared with the SED
group 59.5 (10.4) versus 27.7 (7.8) ms, p<0.05; 5.5 (0.8) versus 2.8 (0.7)%, p<0.05], respectively. Using dynamic BRS testing during the acute orthostatic challenge, the LTET group showed a significantly
higher BRS gain than the SED 6.4 (0.8) versus 3.8 (0.6) ms·mmHg−1, p<0.017] group. These results indicate that CV and BRS are well maintained in healthy, LTET older individuals when compared
with their sedentary peers. Our data suggest that this augmented autonomic cardiac modulation reflects better parasympathetic
responsiveness in LTET individuals. Data provide further support for long-term exercise training as another possible cardioprotective
factor that might decrease susceptibility to ventricular fibrillation as well as assist arterial BP at the onset of an orthostatic
challenge in older men.
Electronic Publication |
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Keywords: | Baroreflex sensitivity Heart rate variability Long-term exercise training Older adults |
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